As is known, there is trend toward miniaturization of electronic products such as mobile phones, tablets, digital cameras, and the like. There is also a demand for development of electronic products which have an increased number of functionalities and have increased electronic capabilities (e.g., increased speed, memory, and operational life). These trends have resulted in a demand for integrated circuits which enable these and other increased capabilities (e.g., increased density, computing power and extended operational life).
In particular, the foregoing trends and demand drive a need for integrated circuits which utilize superconducting materials and properties (so-called “superconducting integrated circuits”). Superconductor materials have substantially no electrical resistance below a certain critical temperature, which may provide for increased performance in integrated circuit devices. The foregoing trends and demand also drive a need for interconnects (or interconnect structures) which enable assembly of semiconductor structures including superconducting integrated circuits.
As is also known, superconducting integrated circuits are a leading candidate technology for large-scale quantum computing. Long coherence times compared to logic gate times are necessary for building a fault tolerant quantum computer. In the case of superconducting quantum bits (qubits), coherence time improvements are attributable to a number of design changes for specific superconducting materials.
One indicator of the coherence time of a superconducting quantum integrated circuit is intrinsic quality factor Qi. Although many studies have been done on qubits, a major technical challenge is the lack of existing high performance integration schemes, which meet the stringent requirements of qubit applications. Such requirements include: maintaining high intrinsic quality factor materials, keeping a substantially high qubit coherence time, reproducibility, and stability over a large temperature range—from room temperature to a few milliKelvin—in addition to the mandatory requirements of scalability.